The invention relates to improvements in powered airships, and more particularly to a powered airship having a flexible envelope inflated and superpressurized by hot air, capable of directed flight for transporting loads over distances and provided with an improved more safe superpressurizing mechanism.
Airships of this type have been referred to as dirigibles and originally referred to as blimps when the airship is nonrigid. The present invention in particular relates to a hot air inflated airship of the nonrigid pressure type. The main envelope or pressure hull is formed of a fabric such as a laminated plastic and Dacron, or of suitable other material which is lightweight, high temperature resistant, extremely strong and impermeable to gas leakage. The envelope of the airship is horizontally elongate and is primarily symmetrical with load lines distributed over the body of the envelope for carrying a payload therebelow. The load lines are alos particularly arranged to support hot gas pressure inflation means which preferably will be in the form of one or more propane fueled burners with a fan inflation means. The fan or blower which pressurizes the airship is driven by a suitable motor which may be propane or gasoline fueled. The airship also carries a propelling engine driving a propeller in order to travel in controlled horizontal flight.
The plastic fabric envelope when not in use can be folded and shipped or stored in the space which takes up less than 1 percent of its inflated volume. The envelope can be relatively rapidly inflated by the operation of the fan and the free lift is controllable by control of the burner which controls the temperature of the air within the envelope. The direction of flight is controlled by tail fins at the aft end of the airship envelope. These tail surfaces preferably include a rigid or stable portion which stabilizes the airship in horizontal flight, and a manipulable portion which changes the direction of flight. Vertically extending control surfaces are pivoted to the left or right to change the direction of flight, and horizontally extending surfaces move up or down to cause the airship to ascend or descend. Primarily, the temperature of the hot air within the airship is controlled to provide sufficient lift for the weight of the envelope and the payload being carried so that essentially free lift is present while the airship is in flight, and it ascends or descends in accordance with the change in angle of the control tail surfaces.
It is important that the airship envelope remain under superpressure, and for this purpose the blower operates continually. The burner is operated intermittently to maintain the temperature of the air within the airship at a predetermined level to provide the free lift needed to carry the payload. Even if the burner should become inoperative for some purpose, if the soft enevelope of the hull can be maintained rigid by the superpressure, the airship can land because the heat loss is gradual and does not occur that rapidly. It is also desirable that the amount of weight carried by the airship be maintained at a minimum, and therefore, auxiliary motors or engines are undesirable. It is, however, critical that the pressurizing blower keep operating, and the failure of the drive motor for the blower could be disastrous.
It is accordingly an object of the present invention to provide a safety arrangement whereby the pressurizing blower for the airship continues operating so that the airship can remain superpressurized in all circumstances.
A further object of the invention is to provide a safety arrangement whereby an auxiliary drive is provided for the superpressurizing blower without necessitating provision of extra unnecessary equipment to add weight to the load carried by the airship.
A further object of the invention is to provide an improved drive arrangement whereby in the event of failure of the blower motor, the blower can be kept operating by the propelling motor so that the airship can be safely landed for repair.
Other objects, advantages and features will become more apparent with the teaching of the principles of the present invention in connection with the disclosure of the preferred embodiment in the specification, claims and drawings, in which: